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SunnyDays

ERA5 almanac — 8 years of real data

Bali in September

Bali in September: rain frequency data not yet backfilled for this month, 77°F average high, 9% of days historically clear (n=240, ERA5 2018–2025).

Bali in September is historically a poor month for sun: only 9% of days clear across 8 years (n=240, avg high 77°F). May is the clearest month for Bali historically. Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live Bali page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late September

Clear-sky percentage for Bali in September, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early September
1st–15th		 8% n=120 77°F
Late September
16th–end		 10% n=120 77°F
Full month average 9% n=240 77°F

Bottom line

Bali is a poor choice for sun in September: just 9% of days clear historically (n=240). May is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ See all destinations in May — historically the best month for sun in Bali.

Every month in Bali

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for Bali, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 3% n=248 All destinations →
February 1% n=226 All destinations →
March 0% n=248 All destinations →
April 8% n=240 All destinations →
May 10% n=248 All destinations →
June 6% n=240 All destinations →
July 5% n=248 All destinations →
August 10% n=248 All destinations →
September ← this page 9% n=240 All destinations →
October 8% n=248 All destinations →
November 2% n=240 All destinations →
December 2% n=248 All destinations →

Frequently asked

Is Bali good for sun in September?

Not usually. Bali is historically overcast in September: only 9% of days are clear (avg high 77°F, n=240 days, ERA5 2018–2025). May is historically far better for sun here.

All percentages are historical averages from the ERA5 reanalysis via Open-Meteo, 8 full years (2018–2025). “Clear” means avg high ≥ 72 °F, precipitation < 1 mm, and a non-precipitation weather code. This is history, not a forecast. The live 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.